Biological response of children to low levels of inorganic lead

Blood lead level (Pb-B), erythrocyte δ-aminolevulinic acid dehydratase (ALA-D), zinc protoporphyrin (ZnPP), and free-erythrocyte porphyrin (FEP) were compared for groups of children of the nursery and primary school living near a lead smelter and in a village 4 km from the factory. A definite increase of Pb-B levels was found in the children living near the lead smelter, who proved to have average values about twice those of the control groups: 17.3 ± 6.9 μg/100 ml for the nursery school and 16.9 ± 5.5 μg/100 ml for the primary school children against 8.7 ± 2.8 and 7.6 ± 2.9 μg/100 ml for the respective controls. A significant decrease of ALA-D activity and an increase of FEP values were demonstrated among the children exposed. For FEP a graded response was evidenced at Pb-B levels ranging between 10 and 20 μg/100 ml blood so that the no-response level in children seems to be lower than 10 μg/100 ml of Pb-B.